The overall-objective of the proposed rsearch is development of a computer-based system which will be capable of using both clinical data and the judgemental knowledge to experts to improve the effectiveness of medical decision-making with regard to clinical therapeutics. Concentrating initially on treatment with antimicrobial agents, its specific goals include: a) development of an interactive program which utlizes data available from the microbiology and clinical chemistry laboratories plus the physician's response to computer-generated questions to provide physicians with consultative advice regarding an appropriate choice of antimicrobial therapy. b) development of an interactive explanation capability to permit the consultation program to explain its knowledge of infectious disease therapy and to justify specific therapeutic recommendations; c) development of a capability for computer acquistion of judgemental knowledge so as to permit experts in the field of infectious disease therapy to teach the system those therapeutic decision rules which they find useful in their clinical practice; d) implementation of the system in the clinical setting at Stanford Hospital; evaluation of the clinical usefulness of the system and of its impact upon the clinical staff and their prescribing practices. The techniques for acquisition, representation, and utilization of knowledge, plus considerations of natural language processing, will draw upon current research in the subfield of computer science known as artificial intelligence.